This view of the twilight sky and Martian horizon taken by NASA's Curiosity Mars rover includes Earth as the brightest point of light in the night sky. Earth is a little left of center in the image, and our moon is just below Earth.

This frame from an animation from NASA's Mars rover Curiosity shows the rover drilling into rock target 'Cumberland.' The drilling was performed during the 279th Martian day, or sol, of the Curiosity's work on Mars (May 19, 2013).

This image from the Mars Hand Lens Imager on NASA's Mars rover Curiosity shows the patch of rock cleaned by the first use of the rover's Dust Removal Tool (DRT). The tool is a motorized, wire-bristle brush on the turret at the end of the rover's arm.

The two bodies in this portion of an evening-sky view by NASA's Mars rover Curiosity are Earth and Earth's moon. The rover's Mast Camera (Mastcam) imaged them in the twilight sky of Curiosity's 529th Martian day, or sol (Jan. 31, 2014).

This image shows the robotic arm of NASA's Mars rover Curiosity with the first rock touched by an instrument on the arm. The rover placed the APXS instrument onto the rock to assess what chemical elements were present in the rock.

This view of Curiosity's deck shows a plaque bearing several signatures of US officials, including that of President Obama and Vice President Biden. The image was taken by the rover's Mars Hand Lens Imager (MAHLI).

This view of the American flag medallion on NASA's Mars rover Curiosity was taken by the rover's MAHLI camera during the 44th Martian sol on Sept. 19, 2012. The flag is one of four 'mobility logos' placed on the rover's mobility rocker arms.

The drive by NASA's Mars rover Curiosity during the mission's 43rd Martian day ended with this rock front of the rover. The rover team has assessed it as a suitable target for the first use of Curiosity's contact instruments on a rock.

This map shows the route driven by NASA's Mars rover Curiosity through the 43rd Martian day, or sol, of the rover's mission on Mars (Sept. 19, 2012). The route starts where the rover touched down, a site subsequently named Bradbury Landing.

Mars has two small, asteroid-sized moons named Phobos and Deimos. This frame from an animation shows the point of view of the rover, located near the equator of Mars, as these moons occasionally pass in front of, or 'transit,' the disk of the sun.

This mosaic from the Mast Camera on NASA's Curiosity rover shows a close-up view looking toward the 'Glenelg' area. One terrain type is light-toned with well-developed layering, which likely records the deposition of sedimentary materials.

This 3-D view of the calibration target for the MAHLI camera aboard NASA's Mars rover Curiosity was assembled from two images taken by that camera during the 34th Martian day. The camera is on the turret of tools at the end of Curiosity's robotic arm.

This image from NASA's Curiosity rover shows the cover on an inlet that will receive powdered rock and soil samples for analysis. The image also shows sand and angular and rounded pebbles that were deposited on the rover deck when it landed.

This image shows the Mars Hand Lens Imager (MAHLI) on NASA's Curiosity rover, with the Martian landscape in the background. The image was taken by Curiosity's Mast Camera on the 32nd Martian day, or sol, of operations on the surface.

This image shows the Alpha Particle X-Ray Spectrometer (APXS) on NASA's Curiosity rover, with the Martian landscape in the background. This image let researchers know that the APXS instrument had not become caked with dust during Curiosity's landing.

This view of the lower front and underbelly areas of NASA's Mars rover Curiosity combines nine images taken by the rover's MAHLI camera during the 34th Martian day, or sol, of Curiosity's work on Mars.

This image taken by the MAHLI camera shows a sample of basaltic rock from a lava flow in New Mexico serves as a calibration target carried on the front of NASA's Mars rover Curiosity for the rover's Canadian-made APXS instrument.

NASA's Mars rover Curiosity carries five cylindrical blocks of organic check material for use in a control experiment if the rover's Sample Analysis at Mars (SAM) laboratory detects any organic compounds in samples of Martian soil or powdered rock.

This view of the three left wheels of NASA's Mars rover Curiosity combines two images that were taken by the rover's Mars Hand Lens Imager (MAHLI) during the 34th Martian day, or sol, on Mars (Sept. 9, 2012).

This view of the lower front and underbelly areas of NASA's Mars rover Curiosity was taken by the rover's MAHLI camera during Sept. 9, 2012. Also visible are the hazard avoidance cameras on the front of the rover.

This view of the calibration target for the MAHLI camera aboard NASA's Mars rover Curiosity combines two images taken by that camera during Sept. 9, 2012. Part of Curiosity's left-front and center wheels and a patch of Martian ground are also visible.

The penny in this image is part of a camera calibration target on NASA's Mars rover Curiosity. The MAHLI camera on the rover took this image of the MAHLI calibration target during the 34th Martian day of Curiosity's work on Mars, Sept. 9, 2012.

The level of detail apparent in this image from Curiosity's Mars Hand Lens Imager (MAHLI) shows that haziness in earlier MAHLI images since landing was due to dust that had settled on the dust cover during the landing.